Direction finder



Feb. 1 9, 1935. f A. TAYLOR 1,991,475

DIRECTION FINDER Filed Jan. 27, 1954 Inventor:

Laurens A'Ta low,

Hi5 Attovne x 1 "Patented Feb. 19, 1935 I a a YDI F NDE I. "Y; Lauren'sAi Taylor, Schenectady;N Yjfassignorto GeneralElectric-Company;- acorporation of;

I I j Application am ze1 4,.s eai ai oasso; 1

a s'c ai s. "(crest-11y I My invention relatesto receivingsystems andmore particularly tosystems used for direction finding radio courseindicating, andIthe-like. y I

A substantially. instantaneously responsive non-- rent a characteristicwhich can be expressed in the. form ofa simple hyperbolic equation asR=Cwhere R is the resis'tancelli is'the'densitywof the currentwin amperes,C is aconstant and the exponent ya' is the slope offlthe curverepresented. by {the equation when plotted with respect .to

15 logarithmiccoordinateay The exponenta is less than unitykandltheIconstant C isybetween the ranges of 10"and 6(l OL Thismaterial'has .the

peculiar 1 property- "of reacting substantially in! stantaneously toasymmetrical voltage or current wave shapes so that a portionof suchwaves is rectified and .a direct current impulse flows .in the circuit;butv when symmetrical wavesoare. passed throughit, nodirect currentflowoccurs;

The direction .of'the direct current flow due toithe partial"rectification o1 asymmetrical wave shapesis-dependent upon whetherthemaximum peakvof the asymmetrical wave is. of positive or negativevalue.

indicates the direction of the radio transmitter. In such systemstheminimum effect isnot particularly'welldefined and it hasbeen found thatradio direction finders which do not work i on the loop' antenna minimumare much more efficient receiving devices and-care capable ofindi toprovide such receiving systems which do notrequire any balancing devicesto secure any relativezbalance of circuits or currents. a In accordancewith my invention,',it has i been ing a certain amount of verticaleffect and an arrangement for symmetrically or sinusoidally reversingthephase or the energy 'collectedby the antenna and impressed upon a;radio receive a simple output circuit utilizing a non-linear reutilizesa directive antenna having a certain found thatby utilizing a directiveantennahaw sistorf' such asThyritea-acts as an extremely economical andreliable direction finder. v

Itis therefore an" object; of my invention to providekan, improvedeconomical direction finder which does Inot-dependupon the loop antennaminimumefiect. i

; The novel features which Ibelieve to be characteristic of my inventionare set forth with particularity in the appended claims, ,My invention"itself however bothaas toitshorganizationand.-methodofoperation,;together with other objects and advantagesthereof, iwill be understood best by reference to' the following'description taken inlconnection with the accompanying" drawing in which Figs. 1and3 diagrammatically illustrate certain characteristics of my. systemand Figs.'2,*' 4=-and 5c are schematic diagrams of variouseinbodimentsofmy invention. I t

rRe'ferring to Fig. l, 1 haveillustrated therein bycurvei A, a,characteristidwhicli" may be. ob-" tained'by a'loop antenna having acertain amount of vertical efiect. If the; connections, from such anantenna to "a receiver bereversed; the. field intensity pattern will betransposed so as to produce theantenna characteristic illustrated by the'dotted line B; Ira radio direction finder- I utilizing suchan antennaand having an out-" a putcircuit provided witha rectifier and a zero- Inradio directionfinders inythe past it has 30 been'comm'on to utilizealoop or directive" an tenna so that the minimumjefl'ect of theantennacenter indicating instrument were to have the connections betweenthe antenna and receiver, and the connections between the receiver andrectifier reversed simultaneously, a radio transmitter located to'therightor left of the point 0- alongthe' line OC'would produce noindication "on' the zero-center indicating instrument inasmuch as theenergy received along 'the line of intersections OC'ofithecharacteristics A and B aieedualn If however the radio transmitterislocatedalong any other line such as thelines OR or 0L,'the-energy'received by the directive antenna will be-unequal, asindicated by these characteristics, since they do not intersect thelines OR or 0L 'atthe same point, and hence the output meter wouldindicate that the transmitter is to the right or ,left of the line 00. I

In accordance with my invention a disclosed in Fig. '2,Ihave'utilizedsuch directive antenna 1 having a certain amount ofvertical efiect soas to produce a characteristicsimilar to that dis-nclosedinFig; l. The directive antenna 1 is connected as a device 2 whichoperates to reverse symmetrically and preferably sinusoidally thephaseof the energy received bythe directive antenna, or in other words,it operates to produce the efiect of sinusoidally reversing theconnections as for instance along the line OR, the sinusoidallyreversing means operates to produce in the receiver output analternating current such as illustrated at B in Fig. 3 which isasymmetrical in form due to a certain amount of a second harmonic beingintroduced into the output of the receiver due to the fact that theenergies received in accordance with the patterns A and B are not ofequal magnitude. In a similar manner, if the transmitter is located tothe left of the line 00, as for instance along the line OL,'thealternating currents appearing in the output'circuit of the radioreceiver will-be of the form illustrated at C in Fig. 3. The purpose ofproducin'galternating currents in the output circuit of the radioreceiver 3 such as illustrated at A",- B and C in Fig.3 willibe apparentlater inconnection with the detailed description of the elements'of the.

circuit arrangement disclosedin Fig. 2.

The directive loop.antenna 1 of Fig. 2'is provided with a capacitor .51inserted atthe midpoint of the antenna. The'ektremities'of the loop an-I tenna adjacent to the capacitor 51 are connected to the terminalsof atransformer .6; The outer extremities of: the loop antenna -1..a'reconnected to the grids of a pairofelectron discharge devices '7andJ8.1Theanodes of thedischarge devices 7 and 8 are connected to atransformer -9 so as to be in push-pullrelatiomthe intermediate point''on the primary winding of this transformer being connected Itothecathode through a suitable source ofanode-pot'ential 10. The cathodesofthe discharge devices 7 and 8. areconnected together and} to an.intermediate point on the second winding=of-transformerfi. The otherwinding of the transformer-6 is connected to a source'of lowyfrequencyalternating current 11. The source of alternating current 11 connectedthrough the transformer/6 operates to produce upon the. grids of:the'-discharge devices.

7 and 8, biasing voltages which operate to, cause the discharge devices7 and 8 alternately to hec'omeconductive and non-conductive in asinusoidal manner. Thus, at one point in the cycle of the alternatingcurrent supplied bythe, source 11, the discharge device 7 is operativeand-the discharge device 8 is inoperativew During the next half cycle,the dischargedevice 8 is operative and'the discharge device 7 isinoperative. [Thus underone operatingcondition of the discharge device,energy of a certain phase is transmitted through thetransformer 9 to theradio receiver 3 and during the next half 'cycleyenergy of the oppositephase is transmitted to the radio receiver mitter with respect to adirection normalgto the alternating currents, and alternating currentcomponents not rectified by the non-linear resistor 12, a by-passcapacitor 14 is connected across the indicating instrument 13. Thenonlinear resistor 12 is preferably of the type described in 'UnitedStates Patent No. 1,822,742, issued September 8, 1931, to K. B.McEachron, but'may be composed of any other material or combination ofelements having the desired nonlinear resistance-current characteristic.

When asymmetrical currents such as shown in the curves B and C in Fig. 3are impressed upon the fThyrite 12, appreciable rectification of suchcurrents occurs, thereby producing direct currentimpulses having apolarity dependent upon the asymmetry of the waves impressed. The directcurrent impulses of different polarity will cause the zero-reenterindicating instrument 13 to'move to the rightor left depending upon thepolarity of the current, thereby giving an indication as to the locationof the radio transmitter with respect to'theline DC of theantennacharacteristic disclosed in Fig. 1.

- In operation, the arrangement disclosed in Fig- 2 when receivingenergy from a transmitter normal to the null position of'the directiveantenna will produce in the output circuit alternating currents of-theform disclosed at Ain'Fig. 3. These alternating currents are notrectified by the nonlinear'resistor' due to its peculiar characteristicwhich operates only-to react .towavejforms of asymmetrical shapel Thusthe alternating currents'of the form A'are passed throughthe nonlinearresistor 12 and shunted past the meter 13 by. the by-pas's capacitor 14;If, however, the direction finder be-rotated so that the transmitteris'l'ocated along the line R with respect.

to it, th'ealternating currents produced in the output circuit-4" ofthe. radio-receiver will be of the form B which when acted upon bythenonlinear resistor 12 produces direct current impulses which causethe needle of the zero-center indicatinginstrument13 to deviateto theright,*thereby Referring to Fig.- 4, I' have disclosed thereina vdirectivefantenna 15 having its midpoint. connected to one side of theinput to the radio receiver 3. The, opposite extremities of thedirective antenna are connected through coupling capacitors 16 and 17 tothe respective anodes of a pair of electron discharge devices Band 19which have their cathodes connected to'the opposite side of the input tothe radio receiver 3. The loop antenna 15 may be'tuned by a variablecapacitor 20. The discharge devices 18 and 19 are of the two-elementtype,',thus: constituting simple .rectifiers which are caused to becomeconductive alternately by theximpression upon the anodes of thedischarge devices of .an alternating current potential supplied from asource 21 through the transformer 22, the opposite terminals of thesecondary winding of which are connected to the anodes of therespective, discharge devices and the midpoint of which is connected tothe oathodes of'the discharge devices. tion,.alternating current fromthe source 21 transmitted through the transformer 22 produces a Thus inopera- 1 poseutubes to generate-audio frequency oscillations" N andsinusoidally to reversethe phase of the endevice 19, while the anode ofthe discharge device 118 isgat -negative potentiaband duringthe nexthalf-cycle the anode of the di'schargeldevice 18 is at positivepotential, while the anode of the dischargedevice 19is at a negativepotential; Thus the discharge devicesl8 and19 operate sinusoidal ly andalternately toconiie'ctathe opposite extremi ties of the loop antenna-15totheradioreceiver 3; thereby producing in the output circuit e of. the

receiver'alternatingicurrents similar to those disdirective loop antenna23 which has :it's midpoint effectively" grounded through the capacitors24 and "25.. The i opposite :eirtremitiesfof t the -direc- .1 tive;antenna 23* are connected to :the grids of: a pair of :discharge devices"261and27 sThese dis charge devices 26 and 127eoperate as dual pure ergyreceived by theantenna 23 as impressed upon the radio receiver 3. ,Theanodes of the dis-.

charge devices 26 and 27. are connectedthrough an inductor 28 so as tocomprise a push-pull oscillator' circuit operating to generate anaudiofrequency which may be for instance, about 2000 cycles per second.A-source of potential29 connected. between an intermediate point on thecenter of the loop antenna 23 adjacent to'the capacitors 24 and 25respectively. Themidpoint of the inductor 30 is connected through asource of potential 31 to thecathodes of, the discharge devices and thissource of potential operates as a biasing potential for the'input gridsofthe discharge devices 26 and 27.. A pair of grids located between theinput grids which are connected to the loop antenna and the anodesoperate as output electrodes for the discharge devices 26 and 27 ofpotential 29; The output circuit of the radio receiver 3, may beprovided with a pair of headphones '33 or other translating device andalso afilter 35 comprising the inductors 36, 37 and the capacitors 38,39 and 40; i This filter network 35 operates to permit only thefrequencies above the frequency of the oscillating circuit 28 to betransmitted through theftransformer 41 to the output circuit 4 whichincludesthe non-linear resistor 12, the zero-centermeter 13 and thebypass capacitor 14.

through the anode circuit which includes the inductor 28 operatetogenerate audio frequency oscillations. which are transmitted throughthe inductor 30 to the input electrodes orgrids of the dischargedevices. hfi fe input grids or electrodes are suitably biased by thesource of? potential 31 so thatthe discharge devices 26 and 27 operatesinusoidally to reverse the phase of the energy received by the antenna"23 as transmitted v e 1,991,475 7 positive impulse upon the anode of thedischarge Letters Patent of the United States is: and are connected tothe extremities of a push* v pull output transformer .32 having itsmidpoint connected to an intermediate point on the source,

through the transformer- 32 to the radio receiver 3. 'Ihealternating'currents "produced in the output circuit ofstheiradio" receiver 3; dueto the action of the discharge device 26 in sinusoidallyreversing thephase of the energy impressed upon the receiver, are similar to thosedisclosedin Fig.

3 and? ofia"frequency:corresponding :to the fre-v quency bf theoscillations generatedv in the circuit-28. The networkfilterf35 preventsany communicationafrequenciest or modulations which may be received bythe headphones 33 from reachingflthe outputcircuite whichincludes theimpedance element 12 having ahyperbolicresistance-currentcharacteristic. 'L'Ihis' non-linear resistor i12linresponsel to asymmetrical currents will produce an indicationupontheindicating device 13 as to the'relative direction of the transmitterwithrespect 'to a direction normal to the null position ofr the'directiveantenna. Y 1. a I While in the preferred-embodiments disclosed in thisapplication, I'have shown and described the meansfor reversing the inputof "the antenna V to "the receiving set: as a sinusoidally" reversingmeans; itis' to beunderstood-that any other symmetrical reversing'meanscould be. used. Such tions. Obviously, ofcourse, the arrangement dis-'closed hasthe advantage that no moving parts are utilized, and nocontacts such as are incurred course, be understood that I do not wishto be limited thereto, since it is apparent that the principles hereindisclosed are susceptible of numerous other applications, and thatmodifications may be made in the circuit arrangements and in theinstrumentalities employed without departing from the spirit and scopeof my invention as set forth in theappended claims; What I claim as newand desire to secure b .1. The combination of a directive antenna/for bycommutators or slip rings are present, in the embodiments disclosed. Itis therefore only necreceiving energy from a radio transmitter, a deltector, means for symmetrically reversing'the phase'of the energyimpressed upon said detector by said antennafwhereby said detectoroperates to produce alternating currents having an asymmetrical formdependent upon the posi'-- tion of said antenna with respect to saidtransmitte'r, andrneans including animpedance de-' 2. The combination'of a radio directive antenna having an unbalanced, receptransmitter, a

said impedance being responsive to asymmetrical currents to produceunidirectionalg'current im h y pulses. I In operation, the dischargedevices 26 and 27, 6

'tion characteristic, a translatingdevice connected to said antenna,means for symmetrically reversing the input of said antenna to saidtranslating device thereby producing in theoutput of said translatingdevice alternating currents'having an asymmetrical form dependent uponthe position of said antenna with respect to said sistance-currentcharacteristic. responsive to asymmetrical alternating currents fortranslate? ing said asymmetrical-alternating currents-intounidirectional current impulses having polarities dependentupon thepositions of said antenna with rrespect to'said transmitter. c 3.. Thecombination of a radioutransmitter, a directive antenna havingarr-unbalanced receptioncharacteristic, 1a translating device connectedto said antenna, means for symmetrically reversing the input oi'saiddirective antenna to said translating device, said reversing means andsaidv translating device cooperating to produce asymmetrical alternatingcurrents whenever said directive antennadeviates from a direction ,nor-'mal tov the. direction of the null positionof said 4. The combination ofa directiveantenna for' receiving energy from a radio transmitter, saidantennahaving an unbalanced reception characteristic, a detector forreceiving energy from said antenna," means for symmetrically reversingthe phase of the energy impressed by said directive antenna upon-saiddetector, said reversing means cooperating with said detector to produceasymmetrical alternating currents having an asymmetry, dependent uponthe relation between the direction of the plane of, said antenna and thedirection of saidtransmitter, and means for antenna having an unbalancedreception char acteri'stic, adetector for receiving energy fromsaid,.antenna,means for sinusoidally reversing the phase-of the energyimpressed by said directive antenna uponv said. detector, said reversingmeans cooperating with said'detector to produce asymmetrical alternatingcurrents having an asymmetry dependent uponthe direction of the plane ofsaid antenna 'withrespectto the directionto said transmitter, and meansincluding an impedance device having a' hyperbolic resist-- ance-currentcharacteristic for receiving said al-.

ternating currents and producing unidirectional V 'LAURENS A. TAYLOR.

25. currents. having a polaritydependentupon the

